Coral 'whisperers' diagnose reef pollution woes

A pioneering project applies concepts of personalised medicine to coral reefs to decode signals that corals put out when under stress from poisons

ROBERT RICHMOND never meant to go to court. Yet there he was before a judge on the Micronesian island of Yap in the Pacific Ocean.

The coral forensics expert at the University of Hawaii was testifying in a case brought by Yap's tribal elders against the owner of the Kyowa Violet cargo ship, which in 2002 had slammed into a reef just outside Yap's main harbour, spewing 200,000 litres of oil into the lagoon.

The elders had turned to Richmond to find out whether the spill had damaged the reef even in areas that were not visibly oiled. As a member of Coral Whisperer, a pioneering project which applies the concepts of personalised medicine to coral reefs, he was the perfect choice.

The project uses scientists from five universities to decode the signals that corals put out when they are under stress. So far, the team has shown that when a coral is exposed to a toxic substance, such as oil, it activates particular genes. These in turn increase the production of enzymes that scrub its cells clean. Different toxins activate different genes, producing a different set of enzymes. So by picking up on changes in the enzymes released by this "defensome", the researchers can diagnose the source of stress.

This is what Richmond did in the Yap case. He collected samples of coral from the reef and sent them to Craig Downs at Haereticus Environmental Laboratory in Virginia for analysis. The results showed that the coral had turned on the genes that code for the proteins cytochrome P450 1 and 2 class, and multixenobiotic resistance proteins (MXR) - the enzymatic hallmarks of oil exposure. In part on the strength of this evidence, the judge ruled in favour of the islanders and in 2006 awarded them $861,600 for damage to the reef.

Since the trial, the project has continued apace. In the coming months, it will launch PdamBase, which will make the defensomes of coral species public so that other researchers can use them, starting with the widespread lace coral, Pocillopora damicornis.

The Coral Whisperer team eventually hopes to create easy-to-use tests that will allow reef managers as well as researchers to monitor coral. Such a kit will become more useful as reefs come under greater threat from pollutants and climate change.

Sometimes the whisperer tests reveal hidden culprits. When the Yap results came back, for example, Downs found that the oil-free coral that was being used as a control had activated the gene that codes for cytochrome P450 6 class - due to organophosphate pesticide. It turned out a farm had sprung up near the reef, and its run-off was sickening the coral in an area thought to be pristine.

This kind of test is particularly useful when more than one factor is at play. In Maunalua Bay, Hawaii, the reason a reef was declining was unknown. Suspects included overfishing, heavy metal pollution, termiticides, pesticides and sediment. Richmond tested samples from various parts of the reef and offered a three-part diagnosis. Near shore, elevated MXR indicated oil pollution; in the middle of the channel, algae and mud were slowly suffocating the corals; and further out, a biomarker suggested termiticides were damaging coral DNA.

The whispering methods may soon play a role in unpicking the greatest environmental disaster of recent years: last year's Gulf of Mexico oil spill. Iliana Baums of Pennsylvania State University, University Park, is not part of the coral whisperer team, but she is using the approach to look at the effects of crude oil and the dispersant Corexit on deep-water corals in the Gulf.

By chance, Baums had just finished sampling the Gulf's black coral, Leiopathes glabberima, when the spill hit. A few months later, she returned to collect more live coral. Her team is now studying the gene expression in both the pre- and post-spill corals. She hopes the results, which should say whether the deep-sea corals were harmed by the oil and dispersants, will be available next year.

These new methods offer some hope in the race to stop the global coral decline. Finding out exactly what is stressing the corals means local people can remove the stressors. This in turn helps the coral cope with more persistent problems like global warming.

Support for this idea came in 2002, when El Niño singed the spectacular corals of the Phoenix Islands in the Pacific Ocean in the worst thermal wipe-out on record. Since then, the reef has made an astonishing comeback thanks to the islands' lack of humans and the pollution they would have imposed. It seems corals can rally against warm waters if they are healthy, which makes a doctor more important than ever.

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